JP2022066646A - Polybutylene terephthalate resin composition - Google Patents

Abstract

To provide a polybutylene terephthalate resin composition which has excellent hydrolysis resistance, flowability, and low warpage.SOLUTION: A polybutylene terephthalate resin composition contains at least (A) 100 pts.mass of a polybutylene terephthalate resin having an amount of terminal carboxyl groups of 1-9 meq/kg or less, (B) a carbodiimide compound, and (C) 10-200 pts.mass of a dimensional accuracy improver, in which an amount of carbodiimide functional groups of the carbodiimide compound is 5-40 equivalents with respect to the amount of the terminal carboxyl groups, and a value obtained by subtracting the amount of the terminal carboxyl groups of the polybutylene terephthalate resin from the amount of the carbodiimide functional groups of the carbodiimide compound is 30 meq/PBT kg or more.SELECTED DRAWING: None

Description

The present invention relates to a polybutylene terephthalate resin composition having excellent hydrolysis resistance, fluidity, and low warpage.

Polybutylene terephthalate resin has excellent mechanical properties, electrical properties, heat resistance, weather resistance, water resistance, chemical resistance, and solvent resistance. Therefore, as engineering plastics, various types of engineering plastics such as automobile parts and electric / electronic parts are used. It is widely used for various purposes.

However, since the main chain of the polybutylene terephthalate resin is due to an ester bond, there is a problem in hydrolysis resistance, and the polybutylene terephthalate resin does not necessarily have sufficient durability when used in a high temperature and high humidity environment.

Further, since the polybutylene terephthalate resin is a crystalline resin, shrinkage anisotropy occurs due to the orientation during injection molding, and the molded product tends to warp. The anisotropy of shrinkage due to orientation is more likely to occur when the polybutylene terephthalate resin contains a fibrous filler.

Therefore, studies have been conducted to improve the hydrolysis resistance and low warpage of the polybutylene terephthalate resin composition from the material aspect. For example, Patent Document 1 discloses a polybutylene terephthalate resin composition in which a carbodiimide compound and a polycarbonate resin and / or a polyethylene terephthalate resin are blended with a polybutylene terephthalate resin containing a fibrous filler.

According to Patent Document 1, the resin composition described in Patent Document 1 is excellent in low warpage resistance and heat shock resistance, and is also excellent in tensile strength retention rate (hydrolysis resistance) after a pressure cooker test. ing. However, in the resin composition described in Patent Document 1, an increase in viscosity due to a reaction between a polybutylene terephthalate resin and a carbodiimide compound becomes a problem. In addition, hydrolysis resistance is not at a sufficient level in response to the increasing demand in recent years.

By the way, in order to improve the fluidity of the resin composition at the time of molding, it is also known to add a fluidity improving agent to the polybutylene terephthalate resin. For example, Patent Document 2 discloses a polybutylene terephthalate resin composition having excellent fluidity, which is a mixture of a polybutylene terephthalate resin and a glycerin fatty acid ester. In this document, a technique for improving hydrolysis resistance is also disclosed. Has not been found.

WO2009 / 150833 Gazette WO2009 / 050859 Gazette

Conventionally, there is a limit to the improvement of hydrolysis resistance by adding a carbodiimide compound, and even if an amount of a certain amount or more is added to the terminal carboxy group of the polybutylene terephthalate resin, the degree of the effect reaches a plateau. Existed, and no further improvement in the effect could be expected.

The present invention has been made to solve such a problem, and an object of the present invention is to provide a polybutylene terephthalate resin composition having excellent hydrolysis resistance, fluidity, and low warpage.

The present inventors have achieved the object of the present invention by the following.

1. 1. A polybutylene terephthalate resin composition containing at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group amount of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent. Therefore, the amount of the carbodiimide functional group of the (B) carbodiimide compound is 5 to 40 equivalents with respect to the amount of the terminal carboxyl group of the (A) polybutylene terephthalate resin, and the amount of the carbodiimide functional group of the (B) carbodiimide compound is (A). The value obtained by subtracting the amount of terminal carboxyl groups of the polybutylene terephthalate resin is 30 meq / PBT · kg or more, and the (C) dimensional accuracy improving agent is (C-1) an alloy resin for improving dimensional accuracy and (C-2). A polybutylene terephthalate resin composition comprising a filler for improving dimensional accuracy and containing 10 to 200 parts by mass of the (C) dimensional accuracy improving agent with respect to 100 parts by mass of the (A) polybutylene terephthalate resin.
2. 2. The polybutylene terephthalate resin composition according to 1 above, which has a tensile strength retention rate of 80% or more in a thermal cycle test based on USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class5.
3. 3. The polybutylene terephthalate resin composition according to 1 or 2 above, wherein the melt viscosity measured at 260 ° C. by ISO 11443 is 0.3 kPa · s or less.
4. (D) The polybutylene terephthalate resin composition according to any one of 1 to 3 above, which contains a polyvalent hydroxyl group-containing compound.

According to the present invention, it is possible to obtain a polybutylene terephthalate resin composition having excellent hydrolysis resistance, fluidity, and low warpage.

Hereinafter, embodiments of the present invention will be described in detail. The present invention is not limited to the following embodiments.

<Polybutylene terephthalate resin composition>
The polybutylene terephthalate resin composition of the present invention comprises at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group content of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent. In the polybutylene terephthalate resin composition containing, (B) the amount of carbodiimide functional groups of the carbodiimide compound is 5 to 40 equivalents with respect to 1 equivalent of the amount of terminal carboxyl groups of (A) polybutylene terephthalate resin, and (B). ) The value obtained by subtracting the amount of terminal carboxyl groups of (A) polybutylene terephthalate resin from the amount of carbodiimide functional groups of the carbodiimide compound is 30 meq / PBT · kg or more, and the (C) dimensional accuracy improving agent is (C-1). It is composed of an alloy resin for improving dimensional accuracy and (C-2) a filler for improving dimensional accuracy, and the (C) dimensional accuracy improving agent is applied in an amount of 10 to 200 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. It is characterized by containing.

In the present invention, when the amount of terminal carboxyl groups of the polybutylene terephthalate resin is as small as 9 meq / kg or less, the improvement of hydrolysis resistance reaches a plateau by adding a large excess of the carbodiimide compound with respect to the amount of terminal carboxyl groups. However, it was found that it would be greatly improved.

<(A) Polybutylene terephthalate resin>
The (A) polybutylene terephthalate resin of the present invention is obtained by polymerizing at least terephthalic acid (terephthalic acid or an ester-forming derivative thereof) and alkylene glycol having 4 carbon atoms (1,4-butanediol) or an ester-forming derivative thereof. It is a thermoplastic resin as a component. The polybutylene terephthalate resin (A) has a terminal carboxyl group amount of 1 to 9 meq / kg.

The base resin (A) polybutylene terephthalate resin (hereinafter, also referred to as PBT resin) is mainly composed of a homopolyester (polybutylene terephthalate) composed of a repeating unit derived from butylene terephthalate or a repeating unit derived from butylene terephthalate. Examples thereof include copolyesters (butylene terephthalate copolymer or polybutylene terephthalate copolyester) having repeating units derived from copolymerizable monomers in the proportions described below.

Examples of the copolymerizable monomer (hereinafter, may be simply referred to as a copolymerizable monomer) in copolyester (butylene terephthalate copolymer or modified PBT resin) include a dicarboxylic acid component excluding terephthalic acid, 1,4-butane. Examples thereof include diols other than diols, oxycarboxylic acid components, lactone components and the like. The copolymerizable monomer can be used alone or in combination of two or more.

Examples of the dicarboxylic acid (or dicarboxylic acid component or dicarboxylic acid) include aliphatic dicarboxylic acids (for example, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedicarboxylic acid, and dodecanedicarboxylic acid. C 4-40 dicarboxylic acids such as hexadecanedicarboxylic acid _and dimer acid, preferably _C4-14 dicarboxylic acid), alicyclic dicarboxylic acid components (eg, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, hymic) _C8-12 dicarboxylic acid such as acid), aromatic dicarboxylic acid component excluding terephthalic acid (eg, phthalic acid, isophthalic acid, naphthalenedicarboxylic acid such as 2,6-naphthalenedicarboxylic acid, 4,4'-diphenyldicarboxylic acid , 4,4'-Diphenoxyether dicarboxylic acid, 4,4'-diphenyl ether dicarboxylic acid, 4,4'-diphenylmethane dicarboxylic acid, 4,4'-diphenylketone dicarboxylic acid and other _C8-16 dicarboxylic acids), or These reactive derivatives (for example, phthalic acid such as dimethylphthalic acid and dimethylisophthalic acid (DMI) _or C1-4 alkyl ester of isophthalic acid, etc.), acid chloride, acid anhydride and the like can be ester-formed. Derivatives) and the like.

Further, if necessary, a polyvalent carboxylic acid such as trimellitic acid or pyromellitic acid or an ester-forming derivative thereof (alcohol ester or the like) may be used in combination. When such a polyfunctional compound is used in combination, a branched polybutylene terephthalate resin can also be obtained.

Examples of diols (or diol components or diols) include aliphatic alkanediols excluding 1,4-butanediol [for example, alkanediols (eg, ethylene glycol, trimethylene glycol, propylene glycol, neopentyl glycol, hexanediol (eg). 1,6-Hexanediol, etc.), octanediol (1,3-octanediol, 1,8-octanediol, etc.), lower alcandiol such as decanediol, preferably linear or branched _C2-12 alkane. Didiols, more preferably linear or branched C _2-10 alcan diols, etc.); (Poly) oxyalkylene glycols (eg, glycols with multiple oxyC _2-4 alkylene units, such as diethylene glycol, dipropylene glycol). , Ditetramethylene glycol, triethylene glycol, tripropylene glycol, polytetramethylene glycol, etc.], alicyclic diols (eg, 1,4-cyclohexanediol, 1,4-cyclohexanedimethanol, hydride bisphenol A, etc.) ), Aromatic diols [eg, dihydroxy C _6-14 arene such as hydroquinone, resorcinol, naphthalenediol; biphenol (4,4'-dihydroxybiphenyl, etc.); bisphenols; xylylene glycol, etc.], and their reactions. Examples thereof include sex derivatives (for example, ester-forming derivatives such as alkyl, alkoxy or halogen substituents) and the like.

Further, if necessary, a polyol such as glycerin, trimethylolpropane, trimethylolethane, or pentaerythritol or an ester-forming derivative thereof may be used in combination. When such a polyfunctional compound is used in combination, a branched polybutylene terephthalate resin can also be obtained.

Examples of bisphenols include bis (4-hydroxyphenyl) methane (bisphenol F), 1,1-bis (4-hydroxyphenyl) ethane (bisphenol AD), 1,1-bis (4-hydroxyphenyl) propane, and 2, 2-bis (4-hydroxyphenyl) propane (bisphenol A), 2,2-bis (4-hydroxy-3-methylphenyl) propane, 2,2-bis (4-hydroxyphenyl) butane, 2,2-bis Bis (hydroxyaryl) C _{1 to} (4-hydroxyphenyl) -3-methylbutane, 2,2-bis (4-hydroxyphenyl) hexane, 2,2-bis (4-hydroxyphenyl) -4-methylpentane, etc. Bis (hydroxyaryl) C _4-10 cycloalkane, 4,4'-dihydroxydiphenyl ether such as ₆ alkane, 1,1-bis (4-hydroxyphenyl) cyclopentane, 1,1-bis (4-hydroxyphenyl) cyclohexane. , 4,4'-Dihydroxydiphenylsulfone, 4,4'-dihydroxydiphenylsulfide, 4,4'-dihydroxydiphenylketone, and alkylene oxide adducts thereof. Examples of the alkylene oxide adduct include C2 _{to 3} alkylene oxide adducts of bisphenols (eg, bisphenol A, bisphenol AD, bisphenol F), for example, 2,2-bis [4- (2-hydroxyethoxy) phenyl] propane. , Diethoxylated bisphenol A (EBPA), 2,2-bis [4- (2-hydroxypropoxy) phenyl] propane, dipropoxylated bisphenol A and the like.

The number of moles of alkylene oxide (C _{2 to 3} alkylene oxide such as ethylene oxide and propylene oxide) added is about 1 to 10 mol, preferably about 1 to 5 mol, with respect to each hydroxy group.

The oxycarboxylic acid (or oxycarboxylic acid component or oxycarboxylic acids) includes, for example, oxycarboxylic acids such as oxybenzoic acid, oxynaphthoic acid, hydroxyphenylacetic acid, glycolic acid, and oxycaproic acid, or derivatives thereof. .. The lactone includes C3-12 lactones such as propiolactone _, butyrolactone, valerolactone, caprolactone (eg, ε-caprolactone, etc.).

Among these copolymerizable monomers, diols [C _{2 to 6} alkylene glycol (linear or branched alkylene glycol such as ethylene glycol, trimethylene glycol, propylene glycol, hexanediol, etc.), and the number of repetitions are preferable. Polyoxy C _{2 to 4} alkylene glycol (diethylene glycol, etc.) having about 2 to 4 oxyalkylene units, bisphenols (bisphenols or alkylene oxide adducts thereof, etc.)], dicarboxylic acids [C _{6 to 12} aliphatic dicarboxylic acids (adipic acid, etc.) Acid, pimelic acid, suberic acid, adipic acid, sebacic acid, etc.), asymmetric aromatic dicarboxylic acid in which the carboxyl group is substituted at the asymmetric position of the allene ring, 1,4-cyclohexanedimethanol, etc.] and the like.

As the (A) polybutylene terephthalate resin, a homopolyester (polybutylene terephthalate) and / or a copolymer (polybutylene terephthalate copolyester) is preferable. In the polybutylene terephthalate resin, the proportion (modification amount) of the copolymerizable monomer is usually 45 mol% or less (for example, about 0 mol% or more and 45 mol% or less), preferably 35 mol% or less (for example,). It may be copolyester of 0 mol% or more and 35 mol% or less), more preferably 30 mol% or less (for example, 0 mol% or more and 30 mol% or less).

In the copolymer, the proportion of the copolymerizable monomer can be selected from the range of, for example, 0.01 mol% or more and 30 mol% or less, and usually 1 mol% or more and 30 mol% or less, preferably 3 mol. % Or more and 25 mol% or less, more preferably 5 mol% or more and 20 mol% or less.

When a homopolyester (polybutylene terephthalate) and a copolymer (copolyester) are used in combination, the ratio of the homopolyester to the copolyester is such that the ratio of the copolymerizable monomer is relative to the total monomer. The range is 0.1 mol% or more and 30 mol% or less (preferably 1 mol% or more and 25 mol% or less, more preferably 5 mol% or more and 25 mol% or less), and usually the former / the latter = 99 /. It can be selected from a range of 1 to 1/99 (mass ratio), preferably 95/5 to 5/95 (mass ratio), and more preferably 90/10 to 10/90 (mass ratio).

(A) The amount of terminal carboxyl groups in the polybutylene terephthalate resin is 1 to 9 meq / kg. A more preferable amount of terminal carboxyl group is 2 to 8 meq / kg, and a more preferable amount of terminal carboxyl group is 3 to 6 meq / kg.

In order to keep the amount of the terminal carboxyl group in this range, a polymer having a high molecular weight having few terminal groups of the polybutylene terephthalate resin may be used, or a melt polymerized product having IV = 0.1 to 0.8 dl / g. May be polymerized by solid phase polymerization and used. When solid-phase polymerization is used, it is desirable to treat at a low temperature for a long time because the terminal carboxyl group increases when the treatment temperature is high, but if the temperature is too low, the polymerization rate is low and the productivity is poor, so it is usually under reduced pressure or not. The temperature can be adjusted, for example, 120 to 220 ° C., preferably 140 to 200 ° C., and more preferably 150 to 190 ° C. in an active gas atmosphere.

Further, when batch polymerization is used, if the resin discharge time after the polymerization is long, the carboxyl group ends increase due to thermal decomposition, so that a resin having a small number of terminal carboxyl groups discharged at the initial stage may be used.

The intrinsic viscosity (IV) of the polybutylene terephthalate resin (A) is preferably 0.6 dL / g or more, and more preferably 0.7 dL / g or more. Further, the intrinsic viscosity is preferably 1.3 dL / g or less, and more preferably 1.2 dL / g or less. By blending (A) polybutylene terephthalate resins with different intrinsic viscosities, for example, by blending polybutylene terephthalate resins with intrinsic viscosities of 1.5 dL / g and 0.5 dL / g, 0.6 to 1.3 dL. Intrinsic viscosities of / g or less may be realized.

The intrinsic viscosity (IV) can be measured in o-chlorophenol under the condition of a temperature of 35 ° C. When a polybutylene terephthalate resin having an intrinsic viscosity in such a range is used, it is easy to efficiently impart sufficient hydrolysis resistance and reduce the melt viscosity.

As the polybutylene terephthalate resin (A), a commercially available product may be used, and terephthalic acid or a reactive derivative thereof, 1,4-butanediol and a monomer copolymerizable if necessary may be used by a conventional method, for example. Those produced by copolymerization (polycondensation) by ester exchange, direct esterification method, etc. may be used.

<(B) Carbodiimide compound>
The (B) carbodiimide compound used in the present invention is a compound having a carbodiimide group (-N = C = N-) in the molecule. As the carbodiimide compound, any of an aliphatic aliphatic carbodiimide compound having an aliphatic main chain, an alicyclic carbodiimide compound having an alicyclic main chain, and an aromatic carbodiimide compound having an aromatic main chain can be used, but they are hydrolysis resistant. In this respect, it is preferable to use an aromatic carbodiimide compound.

Examples of the aliphatic carbodiimide compound include diisopropylcarbodiimide, dioctyldecylcarbodiimide, di-tert-butylcarbodiimide, 1-ethyl-3-tert-butylcarbodiimide, 1- (2-butyl) -3-ethylcarbodiimide, and 1,3-di. -(2-Butyl) carbodiimide, poly (diisopropylcarbodiimide) and the like can be mentioned. Examples of the alicyclic carbodiimide compound include dicyclohexylcarbodiimide and poly (diisopropylcarbodiimide).

Examples of the aromatic carbodiimide compound include diphenylcarbodiimide, di-2,6-dimethylphenylcarbodiimide, di-2,6-diethylphenylcarbodiimide, di-2,6-diisopropylphenylcarbodiimide, and di-2,6-ditert-butyl. Phenylcarbodiimide, N-triyl-N'-phenylcarbodiimide, N- (2,6-diisopropyl-4-phenoxyphenyl) -N-tert-butylcarbodiimide, N, N-bis [3-isosyanato-2,4,6 -Tris (1-methylethyl) phenylamino] carbodiimide, N-cyclohexyl-N- (4- (dimethylamino) naphthyl) carbodiimide, di-o-tolylcarbodiimide, di-p-tolylcarbodiimide, di-p-nitrophenyl Carbodiimide, di-p-aminophenylcarbodiimide, di-p-hydroxyphenylcarbodiimide, di-p-chlorphenylcarbodiimide, di-p-methoxyphenylcarbodiimide, di-3,4-dichlorophenylcarbodiimide, di-2,5 -Dichlorophenylcarbodiimide, di-o-chlorphenylcarbodiimide, di-2,4,6-trimethylphenylcarbodiimide, di-2,4,6-triisopropylphenylcarbodiimide, di-2,4,6-triisobutylphenyl Carbodiimide, p-phenylene-bis-di-o-triylcarbodiimide, p-phenylene-bis-dicyclohexylcarbodiimide, p-phenylene-bis-di-p-chlorphenylcarbodiimide, ethylene-bis-diphenylcarbodiimide mono or dicarbodiimide Compounds and poly (4,4'-diphenylmethanecarbodiimide), poly (p-phenylene carbodiimide), poly (m-phenylene carbodiimide), poly (3,3'-dimethyl-4,4'-diphenylmethanecarbodiimide), poly (naphthic) Lencarbodiimide), poly (1,3-diisopropylphenylenecarbodiimide), poly (1-methyl-3,5-diisopropylphenylenecarbodiimide), poly (1,3,5-triethylphenylenecarbodiimide), poly (diisopropylphenylenecarbodiimide) and Examples include poly (triisopropylphenylene carbodiimide). Two or more of the above carbodiimide compounds can be used in combination.

Of these, di-2,6-dimethylphenylcarbodiimide, poly (4,4'-diphenylmethanecarbodiimide), poly (phenylene carbodiimide) and poly (triisopropylphenylene carbodiimide) are particularly preferably used.

Further, as the (B) carbodiimide compound, it is preferable to use a compound having a number average molecular weight of 2000 or more. By using the (B) carbodiimide compound having a number average molecular weight of 2000 or more, it is possible to improve the hydrolysis resistance of the polybutylene terephthalate resin composition for a long period of time. Further, it is advantageous in that the generation of gas and odor can be reduced even when the residence time of the polybutylene terephthalate resin composition during melt kneading or molding is long.

The amount of the (B) carbodiimide compound in the polybutylene terephthalate resin composition is preferably 5 to 40 equivalents when the amount of the terminal carboxyl group of the (A) polybutylene terephthalate resin is 1 equivalent.

A more preferable blending amount is, when the amount of the terminal carboxyl group of the polybutylene terephthalate resin (A) is 1 equivalent, the amount of the carbodiimide functional group is 6 to 35 equivalents, and most preferably 10 to 30 equivalents. Within this range, a polybutylene terephthalate resin composition having excellent fluidity during molding and mechanical properties after molding can be obtained.

The amount obtained by subtracting the amount of the terminal carboxyl group of the (A) polybutylene terephthalate resin from the amount of the functional group of the (B) carbodiimide compound is 30 meq / PBT · kg or more, more preferably 50 meq / PBT · kg or more. , 70 meq / PBT · kg or more is more preferable. This value is calculated from the amount of each functional group based on 1 kg of PBT.

The amount of carbodiimide functional group means the amount of carbodiimide functional group of the carbodiimide compound in the resin composition, and the carbodiimide equivalent means the amount of carbodiimide functional group of the carbodiimide compound.

<(C) Dimensional accuracy improver>
The polybutylene terephthalate resin composition in the present invention contains (C-1) an alloy resin for improving dimensional accuracy and / or (C-2) dimensional accuracy in order to suppress warpage deformation of a molded product made of the resin composition. (C) A dimensional accuracy improving agent composed of an improving filler is added.

As the alloy resin for improving dimensional accuracy (C-1), not only the shrinkage rate and / or the coefficient of linear expansion during molding and heat treatment is small, but also the processing temperature is close to that of the (A) polybutylene terephthalate resin, and the compatibility is compatible. A good resin can be preferably used.

Examples of the (C-1) alloy resin for improving dimensional accuracy include polyamide resin, vinyl resin, acrylic resin, polyurethane resin, polymer resin, polyphenylene sulfide resin, polyether ether ketone resin, polycarbonate resin, and styrene resin. (Styrene resin, acrylonitrile-styrene copolymer, acrylonitrile-butadiene-styrene copolymer, styrene-butadiene copolymer, styrene-butadiene-styrene copolymer, styrene-isoprene-styrene copolymer, styrene-ethylene-butadiene -Styrene copolymer, etc.), polyarylate resin, polysulfone resin, polyethersulfone resin, phenoxy resin, polyphenylene ether resin, polyetherimide resin, polyamideimide resin, polyacetal resin, unsaturated polyester resin, urea resin, polybutylene terephthalate Polyester resins other than (polyethylene terephthalate resin, polypropylene terephthalate resin, polybutylene naphthalate resin, polyethylene naphthalate resin, polylactic acid resin, etc.), polyolefin resin, olefin elastoma, core shell elastoma, diene elastoma, polyester elastoma, urethane Examples include system-based elastoma, silicone-based elastoma, and combinations thereof.

Among them, amorphous thermoplastic resins such as polyethylene terephthalate resin, polycarbonate resin, polyphenylene ether resin, and styrene resin have a small shrinkage rate and their anisotropy of the molded product, so that the effect of low warpage can be easily obtained. When a liquid additive is contained in the polybutylene terephthalate resin composition, the effect of suppressing bleed-out can be obtained, which is particularly preferable.

Further, polyolefin resins and olefin-based elastomers (ethylene ethyl acrylate copolymers, etc.) have a small decrease in tracking resistance when added to a polybutylene terephthalate resin composition, and therefore, applications in which tracking resistance is particularly required. In, it is also preferable to add these. In addition, in order to improve the affinity between these resins and the polybutylene terephthalate resin, a known compatibilizer may be used in combination.

(C-1) The amount of the alloy resin for improving dimensional accuracy added is 0 to 100 parts by mass, 5 to 90 parts by mass, or 10 to 80 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. May be.

However, depending on the compatibility with the (A) polybutylene terephthalate resin, a good dispersed state cannot be obtained by adding a large amount, and there is a possibility that the mechanical properties of the composition may be deteriorated due to agglomerates and interphase peeling. Therefore, the content of the alloy resin for improving dimensional accuracy (C-1) is preferably 40% by mass or less, preferably 35% by mass or less, based on the entire polybutylene terephthalate resin composition in the present invention. It is more preferably 30% by mass or less, and particularly preferably 25% by mass or less.

(C-2) As the filler for improving dimensional accuracy, an organic filler, an inorganic filler, a metal filler, or a combination thereof can be used, but the processing temperature range and use of the resin molded product can be used. Inorganic fillers and metal fillers having a small shrinkage rate and linear expansion coefficient in the temperature range are preferable. Further, in the molded product used as an insulating member to be combined with the metal member, it is particularly preferable to use an inorganic filler in order to secure the insulating property.

(C-2) The shape of the filler for improving dimensional accuracy includes a fibrous filler, a plate-shaped filler, a spherical filler, a powder-like filler, a curved filler, an amorphous filler, or a combination thereof. However, in order to reduce warpage deformation, it is preferable to use a filler having a small anisotropy. It is more preferable to use a filler having an aspect ratio close to 1, such as a plate-shaped filler, a spherical filler, and a powder-like filler.

On the other hand, when a fibrous filler such as glass fiber is used, the effect of improving mechanical properties such as tensile strength is great, but the anisotropy of the shrinkage rate that causes warpage due to the orientation of the fibrous filler. In the fibrous filler used as the filler for improving (C-2) dimensional accuracy in the present invention, the ratio of fiber length ÷ fiber diameter of milled fiber, whiskers, etc. is 100 or less (preferably 2). ~ 30) short fibers or non-circular cross-section fibers with flat cross-sections such as cocoon-shaped or oval / elliptical (the ratio of major axis / minor axis of cross section is 1.3-10, preferably 1.5-5). The aspect ratio is small. The ratio of these fiber lengths and fiber diameters (including the major axis and the minor axis of the cross section) may be calculated using the values in the catalogs and specifications disclosed by the manufacturers of the fibrous fillers.

Specific examples of the plate-shaped filler include plate-shaped talc, mica, glass flakes, metal pieces and combinations thereof, and specific examples of the spherical filler include glass beads, glass balloons, spherical silica and the like. Examples of the powdery filler include glass powder, talc powder, quartz powder, quartz powder, kaolin, clay, diatomaceous earth, wollastonite, silicon carbide, silicon nitride, metal powder, and inorganic acid metal. Salt (calcium carbonate, zinc borate, calcium borate, zinc tintate, calcium sulfate, barium sulfate, etc.) powder, metal oxide (magnesium oxide, iron oxide, titanium oxide, zinc oxide, alumina, etc.) powder, metal Hydroxide (aluminum hydroxide, magnesium hydroxide, zirconium hydroxide, alumina hydrate (bemite), etc.) powder, metal sulfide (zinc sulfide, molybdenum sulfide, tungsten sulfide, etc.) powder, and combinations thereof, etc. Can be mentioned.

In the molded product used in combination with the metal member, the content of free inorganic acid contained in these (C-2) fillers for improving dimensional accuracy is 0.5% by mass or less, respectively, from the viewpoint of metal corrosiveness. It is preferable that it is.

(C-2) The size of the filler for improving the dimensional accuracy can be appropriately selected in consideration of the balance between the warp reducing effect and the mechanical properties, fluidity and the like. For example, as talc, talc having a volume average particle diameter of 1 to 10 μm or compressed fine powder talc having a bulk specific density of 0.4 to 1.5 can be preferably used, and as mica, a volume average particle diameter of 10 to 10 to 60 μm mica can be preferably used.

These (C-2) fillers for improving dimensional accuracy may be surface-treated (surface coated) with an inorganic compound and / or an organic compound, and examples of the inorganic compound used for the surface treatment include aluminum hydroxide. , Alumina, silica, zirconia, zirconium hydride, zirconia hydrate, cerium oxide, cerium oxide hydrate, aluminum such as cerium hydroxide, inorganic oxides such as silicon, zirconium hydride, cerium, and hydroxides are preferable. ..

Moreover, these inorganic compounds may be hydrates. Among these, aluminum hydroxide and silica are preferable, and when silica is used, silica hydrate represented by SiO ₂ · nH ₂ O is particularly preferable.

The organic compound used for the surface treatment is preferably an epoxy compound or an amine compound, and an epoxy compound such as bisphenol A type epoxy or novolak type epoxy and an amine compound such as monoethanolamine, diethanolamine, triethanolamine and dichlorhexylamine are preferable. Can be exemplified as a more preferable compound.

The amount of the filler (C-2) added for improving the dimensional accuracy is 0 to 100 parts by mass, 5 to 90 parts by mass, or 10 to 80 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. May be. (C-2) The amount of the filler added for improving the dimensional accuracy can be appropriately selected in consideration of the balance between the warp reducing effect and the mechanical properties, fluidity and the like.

The amount of the (C) dimensional accuracy improving agent added, which is composed of the above-mentioned (C-1) alloy resin for improving dimensional accuracy and / or (C-2) filler for improving dimensional accuracy, is (C-1) for improving dimensional accuracy. The total of the alloy resin and the filler for improving the dimensional accuracy is 10 to 200 parts by mass, and 20 to 180 parts by mass or 30 to 150 parts by mass with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. It may be.

<(D) Multivalent hydroxyl group-containing compound>
In the present invention, it is also preferable to add (D) a polyvalent hydroxyl group-containing compound.
(D) The polyvalent hydroxyl group-containing compound is a compound having two or more hydroxyl groups in one molecule. Further, the (D) polyvalent hydroxyl group-containing compound preferably has a hydroxyl value of 200 to 1000.

The polyvalent hydroxyl group-containing compound (D) also enhances the fluidity of the polybutylene terephthalate resin composition. By using the (D) polyvalent hydroxyl group-containing compound, the fluidity of the polybutylene terephthalate resin composition at the time of melting can be efficiently improved while maintaining the characteristics of the (A) polybutylene terephthalate resin at a high level.

Here, the fluidity of the polybutylene terephthalate resin composition is based on ISO11443, and the melt viscosity measured at a furnace body temperature of 260 ° C., a capillary of φ1 mm × 20 mmL, and a shear rate of 1000 sec ^-1 is 0.3 kPa · s or less. It is more preferably 0.25 kPa · s or less, and even more preferably 0.2 kPa · s or less (for example, 0.18 kPa · s or less).

(D) As the polyvalent hydroxyl group-containing compound, a compound produced by a conventionally known method may be used, or a commercially available product may be used.

(D) The hydroxyl value of the polyvalent hydroxyl group-containing compound is preferably 100 or more. Further, the more preferable hydroxyl value is 200 or more, and the more preferable hydroxyl value is 250 or more. When the hydroxyl value is 100 or more, the effect of improving the fluidity tends to be further enhanced, and the effect of improving the hydrolysis resistance can be obtained.

On the other hand, when the hydroxyl value is too large, the reaction with (A) polybutylene terephthalate proceeds excessively, so that the molecular weight of (A) polybutylene terephthalate resin is lowered, and the mechanical properties, heat resistance, and chemical resistance are excellent. There is a risk of impairing the characteristics. The preferred hydroxyl value is 1000 or less, more preferably 500 or less.

The content of the (D) polyvalent hydroxyl group-containing compound in the polybutylene terephthalate resin composition is preferably 0.05 parts by mass or more and 5 parts by mass or less with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. .. More preferably, it is 0.1 part by mass or more and 4 parts by mass or less. More preferably, it is 0.5 parts by mass or more and 3 parts by mass or less.

As the (D) polyvalent hydroxyl group-containing compound of the present invention, it is preferable to use an ether obtained by addition polymerization of a glycerin fatty acid ester or diglycerin with an alkylene oxide. Hereinafter, the ether obtained by addition polymerization of glycerin fatty acid ester and diglycerin with alkylene oxide will be described.

The glycerin fatty acid ester is an ester composed of glycerin and / or a dehydration condensate thereof and a fatty acid. Among the glycerin fatty acid esters, those obtained by using a fatty acid having 12 or more carbon atoms are preferable.

Examples of fatty acids having 12 or more carbon atoms include lauric acid, oleic acid, palmitic acid, stearic acid, 12-hydroxystearic acid, behenic acid, and montanic acid. A fatty acid having 12 or more and 32 or less carbon atoms is preferable, and a fatty acid having 12 or more and 22 or less carbon atoms is particularly preferable.

Specifically, lauric acid, stearic acid, 12-hydroxystearic acid or behenic acid are particularly preferable. It is preferable to use a fatty acid having 12 or more carbon atoms because the heat resistance of the resin tends to be sufficiently maintained. When the number of carbon atoms is 32 or less, the effect of improving the fluidity is high, which is preferable.

Examples of preferred glycerin fatty acid esters are glycerin monostearate, glycerin monobehenate, diglycerin monostearate, triglycerin monostearate, triglycerin stearate partial ester, tetraglycerin stearate partial ester, decaglycerin lauric acid partial ester. , Glycerin mono 12-hydroxystearate and the like.

The ether obtained by addition polymerization of alkylene oxide to diglycerin is, for example, polyoxypropylene diglyceryl ether obtained by addition polymerization of propylene oxide to diglycerin or addition polymerization of ethylene oxide to diglycerin. Examples include polyoxyethylene diglyceryl ether. In the present invention, among these ethers, the use of polyoxyethylene diglyceryl ether is particularly preferable.

<Other ingredients>
The polybutylene terephthalate resin composition of the present invention contains other resins, flame retardants, flame retardant aids, reinforcing fillers, antioxidants, heat stabilizers, and ultraviolet absorbers as long as the effects of the present invention are not impaired. , Antistatic agents, colorants such as dyes and pigments, lubricants, plasticizers, crystal nucleating agents and other conventionally known additives can be contained. In the present invention, it may be preferable to contain a transesterification reaction catalyst and a transesterification reaction terminator as other components.

When the composition contains a transesterification reaction catalyst, the reaction between (A) the polybutylene terephthalate resin and (D) the polyvalent hydroxyl group-containing compound is promoted. If the reaction between the (A) polybutylene terephthalate resin and the (D) polyvalent hydroxyl group-containing compound is slow and it takes time to reach the desired fluidity, a transesterification reaction catalyst can be used to accelerate the reaction. The desired fluidity can be achieved.

The transesterification reaction catalyst is not particularly limited, and for example, a metal compound can be used as the transesterification catalyst. Of these, titanium compounds, tin compounds, and antimony compounds are preferably used.

Specific examples of the titanium compound include inorganic titanium compounds such as titanium oxide, titanium alcoholates such as tetramethyl titanate, tetraisopropyl titanate and tetrabutyl titanate, and titanium phenolates such as tetraphenyl titanate. Specific examples of the tin compound include dibutyltin oxide, hexaethylditin oxide, didodecyltin oxide, triethyltin hydroxide, tributyltin acetate, dibutyltin diacetate, diphenyltindilaurate, monobutyltin trichloride, methylstannoic acid, and ethylstannon. Acids, butylstannonic acids and the like can be mentioned. Examples of the antimony compound include antimony trioxide. Among these, the use of tetrabutyl titanate, tributyltin acetate, and antimony trioxide is particularly preferable.

Further, if the transesterification reaction proceeds too much, the physical characteristics of the molded product obtained by molding the resin composition may deteriorate. By adding a transesterification reaction terminator after the transesterification reaction, the fluidity can be adjusted to a desired level without causing problems such as deterioration of physical properties.

As the transesterification reaction terminator, a phosphorus compound can be preferably used. The type and amount of the phosphorus compound are not particularly limited, and can be appropriately adjusted according to conditions such as the type of the compound contained in the composition of the present invention.

The phosphorus compounds that can be used are not particularly limited, and are phosphine-based, phosphinite-based, phosphonite-based, phosphite-based, phosphinasamide-based, phosphonasdiamide-based, phosphorastriamide-based, phosphoramidite-based, phosphorodiamidite-based, and phosphine. Examples of oxide-based, phosphinate-based, phosphonate-based, phosphate-based, phosphinic amide-based, phosphonodiamidate-based, phosphoramide-based, phosphoramidate-based, phosphorodiamidate-based, phosphinimide-based, and phosphine sulfide-based phosphorus compounds are exemplified. can. Further, the phosphorus compound also includes a compound formed of a metal and a salt.

<Hydrolysis resistant properties>
The molded product made of the polybutylene terephthalate resin composition of the present invention has a tensile strength retention rate of 80% or more in a cold heat cycle test based on USCAR-2 (5.6.2 Temperature / Humanity Cycling) Class5. Moreover, it is preferable that the melt viscosity measured at 260 ° C. by ISO 11443 is 0.3 kPa · s or less.

USCAR-2 is a test condition defined by North American automobile standards, and its Class 5 is -40 ° C (0.5 hours) -80 to 90 ° C and 80 to 100% RH (4 hours) -17 for one cycle. The environmental test conditions at ° C. (1.5 hours) are repeated for 40 cycles.
It is shown that the polybutylene terephthalate resin composition of the present invention is at a level that can be sufficiently used even in the temperature environment of Class 5 thereof.

The tensile strength retention rate is based on ISO527-1, 2 and can be calculated by measuring the tensile strength before and after the test.

<Manufacturing method of polybutylene terephthalate resin composition>
The method for preparing the polybutylene terephthalate resin composition of the present invention is not particularly limited, and generally known equipment and methods can be used as a method for preparing the resin composition. For example, the required components can be mixed and kneaded using a single-screw or twin-screw extruder or other melt-kneading device to prepare pellets for molding.

Further, a plurality of extruders or other melt kneading devices may be used. Further, all the components may be input from the hopper at the same time, or some components may be input from the side feed port. Here, it is preferable to set the extruder cylinder temperature so that the resin temperature in the extruder is 240 to 350 ° C. More preferably, it is 270 to 330 ° C.

When the temperature is lower than 240 ° C., the reaction between the (A) polybutylene terephthalate resin and the (B) carbodiimide compound and / or the (D) polyvalent hydroxyl group-containing compound becomes insufficient, and the polybutylene terephthalate resin composition is resistant to hydrolysis. Due to insufficient properties or high viscosity of the melt, it may not be sufficiently kneaded, and a polybutylene terephthalate resin composition having uniform characteristics may not be obtained. On the other hand, if the temperature exceeds 350 ° C., the polybutylene terephthalate resin (A) is likely to be decomposed, and the mechanical properties and hydrolysis resistance of the polybutylene terephthalate resin composition may be insufficient.

When producing the polybutylene terephthalate resin composition of the present invention, (A) the polybutylene terephthalate resin and (D) the polyvalent hydroxyl group-containing compound are first melt-kneaded, and then (B) the carbodiimide compound and (B). C) A dimensional accuracy improver or a transesterification reaction terminator can also be added. In this case, since the (B) carbodiimide compound is added in a state where the melt viscosity of the (A) polybutylene terephthalate resin is reduced, uniform melt kneading can be efficiently performed.

As a method of adding (B) a carbodiimide compound or the like later, it may be added from the side feed port, or (A) polybutylene terephthalate resin and (D) polyvalent hydroxyl group-containing compound are melt-kneaded and pelletized. After that, (B) a carbodiimide compound and (C) a dimensional accuracy improving agent or a transesterification reaction terminator may be remelted and kneaded to produce the compound.

On the contrary, when (A) polybutylene terephthalate resin and (B) carbodiimide compound are first melt-kneaded and then (D) a polyvalent hydroxyl group-containing compound or the like is added, (A) polybutylene terephthalate resin and (B) carbodiimide compound are obtained. As a result of the reaction of (A), the viscosity of the polybutylene terephthalate resin is increased, so that sufficient melt-kneading with the (D) polyvalent hydroxyl group-containing compound is hindered, and further, heat generation due to shearing increases, and (A) It may lead to thermal decomposition of polybutylene terephthalate resin.

Similarly, when a reinforcing filler is added, if the (A) polybutylene terephthalate resin and (D) the polyvalent hydroxyl group-containing compound are first melt-kneaded and then the reinforcing filler is added, (A) Since the viscosity of the polybutylene terephthalate resin is reduced, breakage of the reinforcing filler due to shearing is suppressed and the mechanical properties are not impaired. Therefore, when the reinforcing filler is used, (A) polybutylene A method of first melt-kneading the terephthalate resin and the (D) polyvalent hydroxyl group-containing compound is particularly preferable.

Further, in the case of (B) the carbodiimide compound and the reinforcing filler, if the reinforcing filler is added first, the reaction between the (A) polybutylene terephthalate resin and the surface treatment agent of the reinforcing filler is not inhibited. A) Since the interfacial adhesion between the polybutylene terephthalate resin and the reinforcing filler becomes stronger, it is preferable in that it is easy to improve the mechanical properties.

Further, the (B) carbodiimide compound can be blended as a masterbatch using a resin as a matrix, and it is often easy to use the masterbatch from the viewpoint of actual handling. A masterbatch made of polybutylene terephthalate resin is preferably used, but one prepared as a masterbatch made of another resin may also be used. In the case of a masterbatch made of polybutylene terephthalate resin, it may be adjusted so as to be within a predetermined blending amount.

Hereinafter, the present invention will be described in more detail by way of examples, but the present invention is not limited thereto. The evaluation was performed in an atmosphere of 23 ° C. and 55 RH% unless otherwise specified.
The compounds listed in Tables 1 to 3 are as follows.

<Material>
(A) Polybutylene terephthalate resin (PBT resin)
A-1: Polybutylene terephthalate resin (intrinsic viscosity = 1.14 dL / g, terminal carboxyl group amount = 4 meq / kg, manufactured by Polyplastics Co., Ltd.)
A-2: Polybutylene terephthalate resin (intrinsic viscosity = 1.14 dL / g, terminal carboxyl group amount = 9 meq / kg, manufactured by Polyplastics Co., Ltd.)
A-3: Polybutylene terephthalate resin (intrinsic viscosity = 0.95 dL / g, terminal carboxyl group amount = 9 meq / kg, manufactured by Polyplastics Co., Ltd.)
A-4: Polybutylene terephthalate resin (intrinsic viscosity = 1.13 dL / g, terminal carboxyl group amount = 12 meq / kg, manufactured by Polyplastics Co., Ltd.)
A-5: Polybutylene terephthalate resin (intrinsic viscosity = 0.84 dL / g, terminal carboxyl group amount = 15 meq / kg, manufactured by Polyplastics Co., Ltd.)

(B) Carbodiimide compound B-1: Stavaxol P100 Carbodiimide equivalent 3625 meq / kg (aromatic carbodiimide compound manufactured by LANXESS Co., Ltd.)

(C) Dimensional accuracy improving agent C-1: Alloy resin for improving dimensional accuracy C-1-1: AS resin (Acrylonitrile-styrene resin 80HF manufactured by Ningbo LG Yongxing Chemical Co., Ltd.)
C-1-2: PC resin (made by Teijin, polycarbonate resin Panlite L-1225W)
C-1-3: PET resin (made by Teijin, polyethylene terephthalate resin TRN-8550FF)
C-1-4: EEA copolymer (manufactured by NUC, NUC-6570)
C-2: Filler for improving dimensional accuracy C-2-1: Talc (manufactured by Matsumura Sangyo Co., Ltd., Crown Talc PP)
C-2-2: Glass flakes (Nippon Sheet Glass Co., Ltd., Microglass Flexa REFG-301)
C-2-3: Flat cross-section glass fiber (manufactured by Nitto Boseki, CSG3PA830 (major axis 28 μm, minor axis 7 μm oval cross section (major axis ÷ minor axis ratio = 4), average fiber length 3 mm oval cross section glass fiber))

(D) Multivalent hydroxyl group-containing compound D-1: Glyceryl hydroxystearate (hydroxyl value 480, manufactured by RIKEN Vitamin Co., Ltd., Rikemar HC100)
(D) The hydroxyl value of the polyvalent hydroxyl group-containing compound was measured by the Japan Oil Chemists' Society 2.3.6.2-1996 hydroxyl value (pyridine-acetic anhydride method).

(others)
Circular cross-section glass fiber: ECS03T-127 manufactured by Nippon Electric Glass Co., Ltd. (average fiber diameter 13 μm, average fiber length 3 mm)
Antioxidant: Phenolic antioxidant (BASF, Ilganox 1010)
Lubricants: Diglycerol tetrabehenate (manufactured by RIKEN Vitamin Co., Ltd., Rikemar B74)
Alkaline compound: Potassium acetate (manufactured by Wako Pure Chemical Industries, Ltd.)

<Examples 1 to 17, Comparative Examples 1 to 6>
(A) Polybutylene terephthalate resin, (B) Carbodiimide compound, (C) Dimensional accuracy improver, (D) Polyvalent hydroxyl group-containing compound, and other components are dry-blended after weighing with the composition shown in Tables 1 to 3. Then, in a twin-screw extruder (TEX-30 manufactured by Japan Steel Works, Ltd.), the cylinder temperature was set to 300 ° C., the screw rotation speed was set to 130 rpm, and the extrusion rate was set to 12 kg / h. The molten resin of the above was cooled and cut with a pelletizer to obtain a pellet-shaped sample of the resin composition. Then, the following various evaluations were performed using these pellets.

[Equivalent ratio of carbodiimide functional group amount to terminal carboxyl group amount]
The amount of terminal carboxyl groups was determined by dissolving the crushed sample of the obtained pellet in benzyl alcohol at 215 ° C. for 10 minutes and then titrating with a 0.01 N aqueous sodium hydroxide solution. Tables 1 to 3 show the measurement results with respect to the amount of the terminal carboxyl group and the equivalent ratio of the amount of the carbodiimide functional group to be mixed.
Equivalent ratio of carbodiimide functional group amount to terminal carboxyl group amount =
Amount of carbodiimide functional group / amount of terminal carboxyl group

[Value obtained by subtracting the amount of terminal carboxyl group from the amount of carbodiimide functional group]
The value obtained by subtracting the amount of the terminal carboxyl group of the polybutylene terephthalate resin from the amount of the carbodiimide functional group of the carbodiimide compound is the amount of the terminal carboxyl group contained in 1 kg of the polybutylene terephthalate resin from the amount of the carbodiimide functional group mixed per 1 kg of the polybutylene terephthalate resin. It was calculated by the following formula as the subtracted value. The values are shown in Tables 1 to 3.
Value obtained by subtracting the terminal carboxyl group from the amount of carbodiimide functional group =
Amount of carbodiimide functional group mixed per 1 kg of polybutylene terephthalate resin-Amount of terminal carboxyl group contained in 1 kg of polybutylene terephthalate resin (meq / PBT · kg)

[Hydrolysis resistance (tensile strength retention rate 1)]
After drying the obtained pellets at 140 ° C. for 3 hours, an ISO3167 tensile test piece was injection-molded at a resin temperature of 260 ° C., a mold temperature of 80 ° C., an injection time of 15 seconds, and a cooling time of 15 seconds, and the test piece was used as a pressure cooker. Tensile strength was measured in accordance with ISO527-1 and 2 before and after treatment with a testing machine at 121 ° C. and 100% RH for 100 hours. The tensile strength retention rate was evaluated as ⊚ when the value calculated based on the following formula was 90% or more, ◯ when 80% or more and less than 90%, and × when the value was less than 80%. The results are shown in Tables 1 to 3.
Tensile strength retention rate (unit:%) = (tensile strength after treatment / tensile strength before treatment) x 100

[Hydrolysis resistance (tensile strength retention rate 2)]
After drying the obtained pellets at 140 ° C. for 3 hours, an ISO3167 tensile test piece was injection-molded at a resin temperature of 260 ° C., a mold temperature of 80 ° C., an injection time of 15 seconds, and a cooling time of 15 seconds. 2 (5.6.2 Temperature / Humanity Cycleing) Based on Class 5, one cycle is -40 ° C (0.5 hours) -85 ° C, 85% RH (4 hours) -175 ° C (1.5 hours). A certain environmental test condition was repeated for 40 cycles, and the tensile strength was measured according to ISO527-1 and before and after the thermal cycle test. The tensile strength retention rate was evaluated as ⊚ when the value calculated based on the following formula was 90% or more, ◯ when 80% or more and less than 90%, and × when the value was less than 80%. The results are shown in Tables 1 to 3.
Tensile strength retention rate (unit:%) = (tensile strength after treatment / tensile strength before treatment) x 100

[Fluidity (melt viscosity)]
The obtained pellets are dried at 140 ° C. for 3 hours, and then measured using a capillary graph 1B (manufactured by Toyo Seiki Seisakusho Co., Ltd.) at a furnace body temperature of 260 ° C., a capillary φ1 mm × 20 mmL, and a shear rate of 1000 sec ^-1 in accordance with ISO11443. The obtained values of 0.2 kPa or less were evaluated as ⊚, those of more than 0.2 kPa and 0.3 kPa or less were evaluated as ◯, and those of more than 0.3 kPa were evaluated as x. The results are shown in Tables 1 to 3.

[Low warpage]
The obtained pellets were dried at 140 ° C. for 3 hours, and then a flat plate-shaped test piece of 120 mm × 120 mm × 2 mm was injection-molded at a cylinder temperature of 260 ° C., a mold temperature of 60 ° C., and a holding pressure of 60 MPa. The obtained flat plate-shaped test piece was allowed to stand at 23 ° C. and 50% RH for 24 hours, and then placed on a surface plate. The coordinates in the height direction were measured with a Mitutoyo CNC image measuring machine, and the amount of warpage of the molded product was calculated from the difference between the highest portion and the lowest portion. The case where the amount of warpage generated was 5 mm or less was evaluated as ⊚, the case where it was 10 mm or less was evaluated as ◯, and the case where it was more than 10 mm was evaluated as ×. The results are shown in Tables 1 to 3.

From the results of Examples and the results of Comparative Examples, it was confirmed that according to the present invention, a polybutylene terephthalate resin composition having excellent hydrolysis resistance, fluidity, and low warpage can be obtained.

Claims (4)

A polybutylene terephthalate resin composition containing at least (A) a polybutylene terephthalate resin (PBT) having a terminal carboxyl group amount of 1 to 9 meq / kg, (B) a carbodiimide compound, and (C) a dimensional accuracy improving agent. Therefore, the amount of the carbodiimide functional group of the (B) carbodiimide compound is 5 to 40 equivalents with respect to the amount of the terminal carboxyl group of the (A) polybutylene terephthalate resin, and the amount of the carbodiimide functional group of the (B) carbodiimide compound is (A). The value obtained by subtracting the amount of terminal carboxyl groups of the polybutylene terephthalate resin is 30 meq / PBT · kg or more, and the (C) dimensional accuracy improving agent is (C-1) an alloy resin for improving dimensional accuracy and (C-2). A polybutylene terephthalate resin composition comprising a filler for improving dimensional accuracy and containing 10 to 200 parts by mass of the (C) dimensional accuracy improving agent with respect to 100 parts by mass of the (A) polybutylene terephthalate resin. The polybutylene terephthalate resin composition according to claim 1, which has a tensile strength retention rate of 80% or more in a thermal cycle test based on USCAR-2 (5.6.2 Temperature / Humidity Cycling) Class 5. The polybutylene terephthalate resin composition according to claim 1 or 2, wherein the melt viscosity measured at 260 ° C. by ISO11443 is 0.3 kPa · s or less. (D) The polybutylene terephthalate resin composition according to any one of claims 1 to 3, which contains a polyvalent hydroxyl group-containing compound.